1. Field of the Invention
The present invention relates to apparatuses and methods that can prolong the lifetime of at least one electric lamp, and particularly to an apparatus and method which can prolong the lifetime of at least one Liquid Crystal Display (“LCD”) backlight lamp.
2. Related Art of the Invention
Images displayed by an LCD are produced by many liquid crystal molecules which do not emit light themselves. Rather, in a typical LCD, one or more high intensity lamps in a backlight module of the LCD illuminate the liquid crystal molecules. For example, one or more cold cathode fluorescent lamps may be employed. The high intensity lamps gradually age over time, which can result in a yellow display. To avoid yellowing and to prolong the lifetime of the lamps, users can adjust the luminance of the lamps to a reduced level, and/or simply turn off the lamps when the LCD is not actually being used.
The technology of prolonging the lifetime of lamps includes power management by way of an associated computer. If no input from a user is received by the computer over a short period of time, the computer automatically shuts off the lamps. Nowadays, computer manufacturers provide shortcut keying to facilitate users in turning off the lamps. In particular, when a user wants to shut off the lamps for a short moment, the user need only press the shortcut keys provided by the computer manufacturer.
However, turning off the lamps in a very short time also wears out the lamps. The sharp changes of current passing through the lamps damage the fluorescent powder of the lamps, and can age the lamps prematurely.
Thus there is a need for an apparatus and method which can not only shut off lamps when they are not needed, but also avoid the sharp changes of current passing through the lamps.